America’s ambassador in London has issued a call for the UK to join Donald Trump in putting pressure on Iran.

Britain and its European allies responded with dismay to Mr Trump’s decision in May to pull out of the 2015 deal which relieved sanctions on Tehran in return to an end to Iran’s military nuclear ambitions.

Foreign Secretary Jeremy Hunt joined with his French and German counterparts last week to voice their “deep regret” at Washington’s withdrawal from the Joint Comprehensive Plan of Action (JCPOA) and vow to protect European companies from US reprisals if they continue to trade with Iran.

London has made clear it is committed to the JCPOA but is open to talking to the US about ways to address shared concerns about Iran’s regional activities.

Woody Johnson urged the UK to reconsider its position on Iran (Stefan Rousseau/PA)

On Tuesday, Foreign Office minister Alistair Burt said that the US had “not got this right” and Britain was ready to stand up to Mr Trump, telling the BBC: “Sometimes you need to take a stand against friends.”

But Ambassador Woody Johnson urged the UK to rethink its position.

In an article in the Sunday Telegraph, he said: “It is time to move on from the flawed 2015 deal.

“We are asking global Britain to use its considerable diplomatic power and influence and join us as we lead a concerted global effort towards a genuinely comprehensive agreement.”

Mr Johnson said the Tehran regime had used the flow of money coming into the country since the easing of sanctions not to improve the lives of ordinary Iranians but to beef up spending on the military and networks of proxy forces and terrorists.

He accused Iran of launching cyber attacks against Western democracies, sponsoring Hizbollah terrorists in Lebanon, arming militants in Yemen and publicly threatening to destroy Israel.

Only by presenting a united front can we exert the maximum possible pressure on the Iranian regime, and get it to finally change course and put an end to its malign and reckless activities both at home and abroad
Ambassador Woody Johnson

“It is clear that the danger from Iran did not diminish in the wake of the deal,” he said. “It grew.

“Far from becoming a more responsible member of the international community, as we had all hoped, Iran grew bolder.”

He called for a “united front” among Western nations to force Tehran into a change of course.

“Only by presenting a united front can we exert the maximum possible pressure on the Iranian regime, and get it to finally change course and put an end to its malign and reckless activities both at home and abroad,” said the ambassador.

“If the regime does make tangible and sustained changes to behave like a normal country, America is prepared to resume full commercial and diplomatic relations. Iran will be free to develop advanced technologies and play a full role in the global economy.

“Until then, America is turning up the pressure and we want the UK by our side.”